To obtain good ink transfer for any particular printing run, various solutions have been disclosed in the form of divided vibrator rollers. For example, Swiss Patent Specification No. 169 362 discloses an inking unit for rotary printing machines, comprising a plurality of vibrator rollers disposed side by side on a common shaft and adapted to be individually brought into and out of operation, the length of each roller corresponding to the width of a printing plate. A control system comprising a plurality of cams of different shapes disposed side by side and longitudinally movable on a common shaft is provided for each vibrator roller. The object of this system is to enable the ink delivery for each individual page with respect to the position of the ink strips to be controlled from a central point during operation.
In East German Patent Specification No. 104 259 there is disclosed a press whose object is to allow programmed adjustment of predetermined and/or calculated metered quantities of ink and obviate any disturbances in ink delivery during continuous printing by control means according to machine requirements. To this end, a system is provided for dispensing the ink in offset and letterpress printing machines without the use of zone screws and duct blades. To obtain a predetermined uniform inking on the sheet in printing solid areas, the ink film thickness required for each ink and paper combination used is obtained by fine adjustment of a nip between the duct roller and a co-acting roller and/or by differential speed between these two rollers. The zone discs are guided with mounting on only one side.
Referring to West German Patent Specification No. 2 924 635 there is disclosed an ink metering system for letterpress and offset printing machines which is substantially independent of paper constituents and damping water and which enables ink to be supplied according to plate inking requirements. This objective is said to be achieved by an ink metering system consisting of a duct and blade and a duct roller with a vibrator for electronic ink zone remote-control in letterpress and offset printing machines, a plurality of ink vibrator wheels being provided, which oscillate individually and independently of one another and the width of each of which corresponds to a specific ink zone.
All these known systems divide the vibrator roller up into a plurality of transfer rollers arranged side by side in the form of discs, each of which has to be laterally supported for positioning purposes. This results in a large gap between the individual ink transfer rollers if the latter are supported on both sides. However, the disclosed mounting is inadequate to take the forces during the transfer of the ink from the duct roller, particularly to a spreader roller rotating at higher circumferential speed. Accordingly, there is always the possibility of lateral deflection during the contact of the vibrator discs and the spreader, because of the narrow mounting plates and since deflection occurs during each contact with the spreader roller there is ultimately the risk of the mounting plate breaking. With regard to the control for the ink vibrator or disc wheels, all that is stated is that this can be carried out as required, but no indication is given of the technical means required. Also, the speed difference between the duct roller and the spreader roller has to be compensated on each contact, and this results in considerable abrasion of the transfer roller surfaces.